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Old March 10th, 2003, 06:51 AM   #16
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We always assume that things work in a linear fashion. What you may me experiencing is a curve in the WB adjust scale. Repeating this with several XL1's might confirm this.
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Old March 10th, 2003, 08:41 AM   #17
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Now all we need John is a minus green example, when you have time of course. ;-)
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Old March 10th, 2003, 09:29 AM   #18
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Sorry for the newbie q - what's the proper usage for these cards and why?
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Old March 10th, 2003, 10:00 AM   #19
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The general idea is to white balance using these cards instead of a white card. Tricks the camera and results in a "warmer" image that some people find more closely replicates reality in some lighting conditions. Purely subjective though.
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Old March 10th, 2003, 10:01 AM   #20
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Simon...

Actually, Adrian and I tried to do those...but it turns out the fluorescents in my building's stairwells and hallways are daylight balanced. How's that for ironic?

I'll see what I can come up with.

Mark, these cards allow you to adjust the white balance so that you can "warm" the image. Video can be somewhat blue, making people look a bit ruddy. By warming them up, it creates better skin tones.

If I were shooting a scene on a Florida beach, they'd be just the ticket. But if I want to shoot a scene in a cold climate, emphasizing the coldness, I wouldn't want to warm the colors.

Depends on the situation.

(Rob...you beat me to it. Posted your answer while I was typing mine ;)
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Old March 10th, 2003, 10:06 AM   #21
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Mark:

I am by no means a pro, but here is what I have gathered so far on the use of cards. I hope some of the pros on the forum will correct me if I'm wrong.

Color temperatures of different kinds of light differ. It basically means that white in daylight is different from white in lightbulb light, flourescent light etc. Your eyes and brain are smart enough to compensate for this, but not a videocamera.

If you use a "home DV" camera, it will often be in auto whitebalance mode. If you look at footage taken in daylight versus footage from indoors in artificial light, there is usually a red shift in indoor shooting meaning that the image will look "too warm". Skin tones will be very reddish etc.

Thus you have the white balance function in the camera. Usually there is a button (in manual mode) that will allow you to set the white balance ie. tell the camera what white is in this light.

The easy way to set it is to hold up a white sheet such as a piece of white paper in front of the camera and hit the white balance button. That will tell the camera what white "looks like" in this particular light. Every time the lighting changes you will have to recalibrate using this procedure.

Now back to the cards... Some people find that using correct white balance will produce images that are slightly "cold" in color. Then you can use white balance cards that are not quite white in order to "cheat" the camera into shooting warmer footage than a true white balance would produce.

The cards have a shift towards blue. The 0 card will be neutral white while the higher the card value, the bigger the blue tint on it.

If you go back and look at the posted examples, you will se a definate change in color temperatur as cards of an increasing value are used.

I hope that explains it a bit.

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Old March 10th, 2003, 10:07 AM   #22
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Hehe. I love this forum. From the time it took from me reading Marks question and till I had finished typing my reply, 2 other people had already answered the question :-)

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Old March 10th, 2003, 10:17 AM   #23
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Hans is right - this forum rocks.

Thanks for the explanations everyone.
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Old March 10th, 2003, 10:58 AM   #24
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A few thoughts.

Number One: when we shoot film or video, the idea is to create pictures that flatter our subjects (unless we have an ulterior motive). This is what film people have known for years. Therefore, film is manufactured with a bias toward magenta for warmth. (This is a very simple explanation)

Video, on the other hand, was meant to recreate reality, and what it ended up with was a somewhat "cool" or blue bias. Recently, that bias has been recognized and improvements made to the standard set-up on most cameras. My Sony PD150 has a much warmer image than the first Betacam I operated many years ago.

I think some of you hit the nail on the head. In John's pix, what the normal white balanced pictures need is an adjustment to the contrast more than a "warming" with white balance. Take one of the uncorrected stills into Photoshop and see if you can improve the quality of the picture with levels or curves.

In general, I see too much of a shift toward yellow in the stills. Just my opinion.

When we talk about warming up a picture, what we are usually refering to, is moving skin tones toward a warmer shade. The problem with "fooling" the white balance of the camera, is that it makes a global shift in the chroma, so that everything "warms" up. This is not always desireable. For instance, using blue to warm a face means that a blue suit or shirt will shift toward brown.

What you are trying to do with the warm cards is what film people do in timing or color correction. But it is much better to do this in post where you can make critical decisions in a dark environment, and compare pictures you shot on Monday with pictures from Friday. But if you have already made global corrections to the picture, you now have to eliminate the correction and try to establish a "standard," which is what you have effectively eliminated with the use of the warm cards.

Remember that all white items are not created equal. It is best to settle on a white card and use that one card consistently. The original Kodak "grey cards" had a white side that was very handy. These cards apparently are being phased out by Kodak for the much more expensive "Grey card Plus." But this is a good card to use, as it presents you with white, grey and black on the same surface. Shoot a bit of the card at the head of the scene to use with color correction tools in post.

Professional shooters have been using "cheats" for white balance as long as there have been Betacams. Most have abandoned the cheats for (1) setting up the cameras with a more favorable gamma (2) fix it in post. But certainly many new people are experimenting with the white cards. I think they will abandon them after a period of time.

Just my 2
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Old March 10th, 2003, 11:47 AM   #25
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Sheesh...tough crowd. Thought I could get away with slapping them up there quickly as long as they showed the hue change. ;)

Okay...the first group, "Outdoor Sunny Day," has been reuploaded. These shots are pristine...straight out of the camera condition except for resizing. They were taken with the camera in automatic (not full "green box" auto) exposure. No adjustments of any kind have been made to them.
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Old March 10th, 2003, 12:12 PM   #26
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Another thing to bear in mind is the advantage one has in altering the "look" in camera. Too much emphasis is placed on doing things in post. If you feel a "warmed" up image is what you're after for a particular project then best to try and get that look right from the start. You don't after all want to have to render all your footage and loose any quality (assuming you stay with the DV codec) if all you require a slight warming up of the image.

After all, look how for years DPs have been altering the look of film in camera.

Now, if only someone could figure out how to do pre-flashing on in-camera DV.

(I know I've over simplified the above statements and there are other issues to take into consideration. But I hope you get my point.)
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Old March 10th, 2003, 01:19 PM   #27
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<<<After all, look how for years DPs have been altering the look of film in camera.>>>

As a matter of fact, the trend recently has been to do the "altering" of the look in post, due to the possibilities of working with the intermediary in digital color correction. Witness films such as "Amelie." "Oh Brother." You can expect much more of this in the future. For "newbies" who are becoming aware of the possibilities of filters and color correction, certainly experimenting with cheats, such as using warm cards is a valid part of the educational process. But be aware of the limitations. Especially if you cannot schlep a professional monitor on all your shooting safaris.
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Old March 10th, 2003, 01:33 PM   #28
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Simon-X:

Please contact me via e-mail, regarding the note in my sig file below -- thanks,
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Old March 10th, 2003, 02:41 PM   #29
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<<<-- Originally posted by Wayne Orr : <<<After all, look how for years DPs have been altering the look of film in camera.>>>

As a matter of fact, the trend recently has been to do the "altering" of the look in post, due to the possibilities of working with the intermediary in digital color correction. Witness films such as "Amelie." "Oh Brother." You can expect much more of this in the future. For "newbies" who are becoming aware of the possibilities of filters and color correction, certainly experimenting with cheats, such as using warm cards is a valid part of the educational process. But be aware of the limitations. Especially if you cannot schlep a professional monitor on all your shooting safaris. -->>>

Very true. I just feel there's too much reliance on doing things in post without bearing this in mind when actually shooting.

In all your examples the DPs had planned to alter the film in post, consequently they shot the film with this in mind and altered their methods to better achieve their chosen look.

We don't, after all, want to be like George Lucas and think we can do everything in post. That way just looks rubbish.
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Old March 10th, 2003, 02:47 PM   #30
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Warm cards are just one tool in your arsenal. Some projects do not have the time and, or the budget to do fixes in post. The loss of quality due to rendering is also an issue for many people.

Post is also a tool that allows us to adjust parameters way beyond what can be achieved in the camera. The trick is to know which is the best method to apply to your project. However, I am a firm believer in shooting it correctly in the camera if at all possible. This usually saves my clients time and money. But estimate wrong and the improper WB or other in camera effects can lead to costly fixes in post.
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